What to do with this endlessly problematic play? Directors such as Peter Zadek and David Thacker set it in the stock exchange. But Rupert Goold, as is his wont, goes for broke by transporting it wholesale to modern Las Vegas, where showbiz fantasy meets speculative capitalism; and the result is, by turns, brilliant, outrageous and excessive.

At first I had difficulty working out the logic of the setting: why, in particular, should Patrick Stewart's multi-millionaire property-owning, semi-assimilated Shylock feel an "ancient grudge" towards the local Christians? And could we really believe they would void their spittle upon him in the wide streets of the US gambling capital?

But, scene by scene, the concept begins to make sense: we realise that wealth is no barrier against ingrained anti-semitism and Stewart's Shylock, however comfortable he may seem, is secretly despised and he is reduced, presumably because denied access to the golf clubs, to trying a few putting shots in his office. And, the greater his sense of isolation, the more he Shylock reverts to his ancestral religion.

But where Goold's production really breaks the mould is in its treatment of Portia. The casket-scenes are turned into a TV game-show called Destiny in which Susannah Fielding's stunning Portia dons a blonde wig and southern accent; she becomes, as it were, the hostess of a preposterous lottery in which her marital future is being decided. This not only provides wonderful comedy with the Prince of Morocco turning up as an avaricious contestant in golden boxing-shorts. It also achieves a startling final payoff when Fielding's Portia confronts the reality behind the make-believe; which is that Bassanio is more truly in love with Scott Handy's seductively melancholic Antonio than he is with her.

This is a dazzling production that gathers strength as it goes along. It may seem a gimmick to have Launcelot Gobbo played by Jamie Beamish as an Elvis impersonator, but it yields a handsome return when Portia's climactic breakdown is accompanied by the strains of Are You Lonesome Tonight.

And the full force of both the persecution of "aliens" and Shylock's concomitant revenge emerge in a remarkable trial scene: not a judicially correct event but an undergound, quasi-legal proceeding in which Antonio is clad in the orange suit of a political prisoner and the Mafioso duke is surrounded by pistol-packing henchmen. It becomes a vision of the American nightmare; but the whole point of this daring and innovative production is that Shakespeare's play itself takes us into an imaginary dreamscape in which reality eventually intrudes. And, although Goold's production is bound to cause argument, Las Vegas seems a perfect metaphor for a world of financial and romantic fantasy.